Comparison of Two Prophylactic Norepinephrine Doses for Prevention of Post-Spinal Hypotension on Umbilical Artery and Vein Blood-Gas Parameters in Patients Undergoing Elective Caesarean Section: A Randomized Controlled Study

Spinal anaesthesia is the preferred technique for an elective caesarean section as it decreases airway manipulation and other potential complications related to GA1. Hypotension is the most common complication of spinal anaesthesia during caesarean delivery. As it can have adverse effects on the mother as well as the foetus, timely management of post-spinal hypotension is extremely important. Although various methods have been tried to reduce the incidence, vasopressors remain the mainstay of management of post-spinal hypotension.

Most common vasopressors used are phenylephrine, ephedrine and norepinephrine. Phenylephrine causes decreased maternal heart rate and subsequent fall in cardiac output. Ephedrine causes maternal tachycardia and decreases fetal pH. Norepinephrine has emerged as an effective prophylactic vasopressor with a favourable balance between maintaining maternal blood pressure and minimizing reflex bradycardia. Norepinephrine has dual alpha and beta agonist activity maintaining maternal cardiac output.

Current evidence on noradrenaline use in obstetric anaesthesia focuses mainly on maternal hemodynamic outcomes (blood pressure, heart rate, incidence of hypotension).Foetal outcomes, particularly blood gas parameters, are underexplored.

Comparative data between different prophylactic dosages of noradrenaline and their impact on foetal physiology are lacking. Although there are abundant literature2 about norepinephrine infusion and bolus in caesarean section, but till recently no study has been done in Indian population comparing the effect of different doses of norepinephrine on Foetal blood gas parameters.

This study addresses this gap by providing data on umbilical cord blood gases following two distinct norepinephrine prophylaxis regimens, thereby offering new insight into fetal acid–base balance in the context of spinal anaesthesia for caesarean delivery. This study aims to compare norepinephrine 0.04mcg/kg/min, 0.08mcg/kg/min and a placebo on fetal blood gas parameters in Indian population.